NEW YORK (Reuters Health) - Education campaigns that aim to
inform people about the benefits of vaccines do little to
increase the intent of parents to vaccinate their future
children, according to a new study.

Furthermore, researchers found that among a group of parents
who were least likely to vaccinate their future children, some
education campaigns actually added to their reservations.

The study's lead author told Reuters Health that the
research is an extension of his work in political science that
found it is difficult to correct people's misinformation.

"We found political misinformation is often very difficult
to correct and giving people the correct information can
backfire," said Brendan Nyhan, a political scientist at
Dartmouth College in Hanover, New Hampshire.

"We were interested in seeing if the messages public health
agencies were putting out were effective," he said.

Specifically, Nyhan and his colleagues examined public
health campaigns about the measles-mumps-rubella (MMR) vaccine.

Although national U.S. MMR vaccination rates are high, the
researchers write in Pediatrics that there are states where the
rate dips below 90 percent, which is a commonly used threshold
for so-call herd immunity. Herd immunity is the point where high
vaccination rates within a population may also offer protection
to the unvaccinated.

They also write that maintaining high levels of MMR
vaccination is important because of the increasing number of
measles cases reported in the U.S. and recent outbreaks in the
UK. Measles is a highly contagious respiratory disease that can
lead to death.

Another study published by Centers for Disease Control and
Prevention (CDC) researchers in the same journal found that
vaccinating U.S. kids born in 2009 according to the routine
immunization schedule will save about $70 billion and prevent
over 40,000 early deaths and over 20 million cases of disease.

For their new study, Nyhan and his colleagues used data from
nationally representative surveys conducted in June and July
2011 of 1,759 parents who were at least 18 years old.

During one survey, parents were asked for general
information about the health of their children and about their
attitudes toward vaccination.

The parents were then randomly assigned to receive one of
five messages an average of 12 days later and surveyed again
after that.

The first message or campaign used information from the CDC
to correct misinformation that the MMR vaccine causes autism, a
belief that has been disproven.

The second and third campaigns also used materials from the
CDC to present information on the risk of the preventable
diseases or a story about one woman's experience with her son
being hospitalized with measles.

The fourth campaign consisted of pictures of children who
had each disease.

Another group of parents was asked to read information about
the cost and benefits of bird feeding to act as a comparison
group.

During the second survey, there was no significant increase
in parents' intents to vaccinate their future children, but
those who received the CDC information debunking the link
between the MMR vaccine and autism had fewer misperceptions
about that topic.

However, among the one third of people who were least likely
to vaccinate any future children they may have, getting those
same materials was linked to an even lower likelihood that they
would vaccinate.

That strengthening of convictions among the least likely to
vaccinate may be due to those people coming up with other
arguments to support their beliefs, the researchers write.

"We can't look inside their head," Nyhan said, adding that
it's a theoretical interpretation but consistent with other
research.

The researchers also found the campaigns aimed at stressing
the dangers of the preventable diseases only increased parents'
misperceptions.

"We need to test public health messages of all sorts to see
if they're effective - especially with some sub-populations that
may be resistant to some public health messages," Nyhan said.

Dr. Mary Healy said it's also important that there not be
just one mass-market public health campaign addressing vaccines.

"This is very important research, because any public health
campaign we release we have to make sure they're effective,"
said Healy, from the Center for Vaccine Awareness and Research
at Texas Children's Hospital in Houston. She was not involved
with the new research.

Healy said the study also emphasizes the role of the
relationship between the parent and healthcare provider in
clearing up misinformation.

"If I had any message, you need to talk to your healthcare
provider and bring your worries to your healthcare provider,"
she said.